Bell-bottom modular stent-graft

ABSTRACT

A system for repairing body lumens including a modular graft and a method for deploying the graft within the body lumen. The modular graft includes a first component having first and second leg portions which mate with second and third graft components, respectively. The second leg portion has a bell bottom shape. The modular graft further includes expandable members which aid in implanting the modular graft as well as facilitates the mating of its components. In order to repair the body lumen, the first component is placed at the repair site and thereafter, the first and second legs are advanced to the repair site and attached to the first component.

This application is a continuation of application Ser. No. 09/014,945filed Jan. 28, 1998, now U.S. Pat. No. 6,030,415 and also claims benefitof Provisional No. 60/036,518 filed Jan. 29, 1997.

FIELD OF THE INVENTION

The present invention is directed to an intraarterial prosthesis, amodular stent-graft, for repair of abdominal aortic aneurysm (“AAA”herein).

BACKGROUND OF THE INVENTION

An intraarterial prosthesis for the repair of AAAs (grafts) isintroduced into the AAA through the distal arterial tree incatheter-based delivery systems, and is attached to the non-dilatedarteries proximal and distal to the AAA by an expandable framework(stents). An intraarterial prosthesis of this type has two components: aflexible conduit, the graft, and the expandable framework, the stent (orstents). Such intraarterial prosthesis used to repair AAAs is namedstent-graft. AAAs typically extend to the aortic bifurcation of theipsilateral femoral artery and the contralateral femoral artery. Thereis rarely any non-dilated aorta below the aneurysm, and thus the distalend of the graft must be implanted in the iliac arteries, and for thegraft to maintain prograde in-line flow to the legs and arteries of thepelvis, it must also bifurcate. Currently available stent-grants fallinto two categories. The first category of stent-grafts are those inwhich a preformed bifurcated graft is inserted whole into the arterialsystem and manipulated into position about the AAA. This is a unitarystent-graft. The second category of stent-grafts are those in which abifurcated graft is assembled in situ from two or more stent-graftcomponents. This latter stent-graft is referred to as a modularstent-graft.

SUMMARY OF THE INVENTION

The present invention is directed to a modular stent-graft comprisingmulti-components. The modular stent-graft of the present inventioneliminates or avoids the main drawbacks common to the currentlyavailable modular stent-grafts for repair of AAAs. Stent-grafts areinserted into the AAA through the femoral arterial system. The graftmust bridge the AAA and form a leak-proof conduit between the aorta andthe femoral arteries. The surgeon can only view the operation by X-raytechniques and yet the surgery is performed in a three-dimensionalenvironment. This is a demanding regime and requires a trained andskilled surgeon.

The main drawbacks common to the current modular stent-grafts are:

(1) The connection site between the stent-graft components is prone toleakage and a separation of the components which allows blood to leakdirectly into the AAA restoring the potential for rupture. If the AAAruptures, the result is frequently the death of the patient.

(2) The connection site on the first stent-graft component is oftendifficult to catheterize prior to introduction of the second stent-graftcomponent. The necessary instrumentation required to insert cathetersand carry out the repair of the abdominal aneurysm can dislodge muralthrombus in the AAA. The dislodged mural thrombus is carried in theblood flow through the femoral arteries to small distal arteries causingblockage and tissue necrosis.

The modular stent-graft of the present invention consists of threestent-graft components. The first stent-graft component resembles a pairof shorts with the trunk proximal and the two legs or docking sitesdistal. The second and third stent-graft components are tubes of almostuniform diameter that extend from the primary stent-graft componentdocking sites, through the AAA, to the femoral arteries. The completedmodular stent graft bridges the AAA from the abdominal aorta to thefemoral arteries. The proximal ends of the second and third stent-graftcomponents, i.e., ends nearest the aorta, are inserted into the dockingsites of the primary stent-graft. The second stent-graft component isinserted through the ipsilateral arteries to the ipsilateral dockingsite of the primary stent-graft component. The second stent-graft isalso referred to as the ipsilateral extension. The third stent-graftcomponent is inserted through the contralateral arteries to thecontralateral docking site through the bell-bottom portion of theprimary stent-graft component. The third stent-graft is also referred toas the contralateral extension.

The modular stent-graft of the present invention has a number ofdistinguishing elements. The stents that hold the two docking sites openare at different levels and are of different sizes. On the ipsilateraldocking site, the stent is within the docking site. With regard to thecontralateral docking site, the stent is within a wider distal segment,the bell-bottom segment below the contralateral docking site.

Because the distal stents of the primary stent-graft component are atdifferent levels, one below the other, they occupy different segments ofthe delivery system. Since the stent-graft components are delivered tothe AAA though a narrow catheter, they must be reduced to the smallestpossible diameter to effect and ease delivery. By separating thestent-graft into three components, the necessary stents can be arrangedat different levels permitting them to be as large as possible. Sincethe distal stents can be larger in a modular system than in a unitarysystem, the distal orifice of the ipsilateral and contralateral dockingsite can be large and thus easier to catheterize for the delivery. Thisis only important on the contralateral side, that is, the side with thecontralateral docking site. On the ipsilateral side, that is, the sidewith the ipsilateral docking site, catheters can be introduced over thesame guide wire that was used to introduce the first stent-graftcomponent through the arterial system to the AAA. In practice, thedistal orifice of the contralateral docking site can be at least aslarge as the trunk of the primary stent-graft component. The firststent-graft component 12 and the second and third stent-graft components14 and 16 can be made of the same different biologically inert graft andstent material, such as biologically inert knit or woven fabric, ormembrane material, such as PTFE membrane material, and springy material,such as stainless steel or titanium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the modular stent-graft of thepresent invention implanted to repair an abdominal aortic aneurysm;

FIG. 2 is a front perspective view of the first stent-graft component ofthe modular stent-graft of FIG. 1;

FIG. 3 is a cross-sectional view of the first stent-graft component ofFIG. 2;

FIG. 4 is a top fragmentary cross-sectional view of the stent-graft ofFIG. 1;

FIG. 5 is an enlarged fragmentary cross-sectional view of the connectionbetween the first stent-graft component and the third stent-graftcomponent of the stent-graft of FIG. 1;

FIG. 6 is a cross-sectional view of the second stent-graft component ofthe modular stent-graft of FIG. 1;

FIG. 7 is a front perspective view of an alternative embodiment of thefirst stent-graft component of the modular stent-graft of the presentinvention;

FIG. 8 is a cross-sectional view of a second alternative embodiment ofthe first stent-graft component of the modular stent-graft of thepresent invention; and

FIG. 9 is a front perspective view of a third alternative embodiment ofthe first stent-graft component of the modular stent-graft of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the modular stent-graft 10 of the present inventionis illustrated implanted to repair an abdominal aorta aneurysm 28. Themodular stent-graft 10 comprises a first stent-graft component 12 havinga proximal end 13A and a distal end 13B, second stent-graft component14, often referred to as the ipsilateral extension, and a thirdstent-graft component 16, often referred to as the contralateralextension. The three components comprise sheaths or grafts 41, 21 and 23containing self-expanding stents (not shown in FIG. 1). The proximal end13A of the trunk 40 of the first stent-graft component 12 is implantedin the proximal implantation site 30 in a non-dilated portion of theabdominal aorta 22. The proximal end 36 of the second stent-graftcomponent, or ipsilateral extension, is connected to the firststent-graft component at the ipsilateral docking site 18. The proximalend 37 of the third stent-graft component 16, or contralateralextension, is connected to the first stent-graft component at thecontralateral docking site 20. The distal end 38 of the secondstent-graft component is implanted in the undilated portion of theipsilateral iliac artery 24 at the ipsilateral distal implantation site32. The distal end of the third stent-graft component, or contralateralextension, is implanted in a non-dilated portion of the contralateraliliac artery 26 at contralateral distal implantation site 34, as will bedescribed herein. The contralateral leg 15B of the first stent-graftcomponent terminates in a bell-bottom 42. Bell-bottom aids in thesurgical implantation and manipulation of the modular stent-graft in theaorta and the aneurysm 28 as will be described below.

The ipsilateral catheter guide wire 80 is shown coming up from theipsilateral arteries (the isilatoral femoral artery and ipsilateraliliac artery) into the ipsilateral extension through the ipsilateraldocking site and out through the proximal end 13A of the trunk 40. Thecontralateral catheter guide wire 82 is shown extending up from thecontralateral femoral artery through the contralateral iliac artery andthrough the contralateral extension 16 through the contralateral dockingsite 20 and out through the proximal end 13A of the trunk 40. Normally,both guide wires are left in until the completion of the operation.After the modular stent-graft has been successfully implanted to repairthe abdominal aortic aneurysm, the guide wires are removed. In thepreferred embodiment, the ipsilateral catheter guide wire 80 is firstinserted to permit the delivery of the first stent-graft component andthe ipsilateral extension into the AAA. The contralateral catheter guidewire 82 is inserted from the contralateral iliac artery 26 into thecontralateral docking site 20 of the first stent-graft component. Asmentioned above, the surgeon is viewing the three-dimensionalenvironment of the AAA with a two-dimensional X-ray screen. The largebell-bottom 42 of the first stent-graft component eases the surgeon'stask in successfully snaking the guide wire 82 up into the bell-bottom42 and into the contralateral docking site 20. Obviously when the firstguide wire 80 is inserted, the surgeon is concerned with having theguide wire come out of the ipsilateral iliac artery 24 through the AAAinto the abdominal aorta 22. Without the bell-bottom 42 below thecontralateral docking site 20, it would be very difficult, and in manyinstances impossible, to successfully snake the contralateral catheterguide wire 82 into the contralateral docking site 20 of the firststent-graft component.

Referring to FIGS. 2 and 3, the first stent-graft component 12 of themodular stent-graft 10 comprises a trunk 40 at the proximal end 13A ofthe first stent-graft component and ipsilateral leg 15A andcontralateral leg 15B at the distal end 13B of the first stent-graftcomponent. The distal end of the ipsilateral leg 15A has a constrictedportion 62. The contralateral leg 15B has a constricted portion 64 atapproximately the same level as constricted portion 62. A radioopaquemarker 66 is placed on the first stent-graft component in theconstricted portion 64 adjacent the constricted portion 62, as shown inFIG. 2. This marker aids the surgeon in positioning the proximal stentsof the ipsilateral and contralateral extensions. The first stent-graftcomponent is delivered into the aorta aneurysm 28 via a conventionalstent-graft catheter delivery system, such as disclosed in U.S. Pat.Nos. 4,580,568; 4,655,771; 4,830,003; 5,104,404; and 5,222,971. Themodular stent-graft has three self-expanding stents: a proximal trunkstent 48, situated within the first stent-graft component at theproximal end 13A; an ipsilateral trunk stent 50, positioned within thefirst stent-graft component near the distal end 13B of the ipsilateralleg 15A; and a bell-bottom stent, located within the bell-bottom 42 atthe distal end 13D of the contralateral leg 15D. These areself-expanding stents of the conventional type, such as disclosed inU.S. Pat. Nos. 4,580,568; 4,655,771; 4,830,003; 5,104,404; and5,222,971. My self-expanding stent disclosed in U.S. patent applicationSer. No. 08/582,943 can be used.

The stents employed in the present invention are self-expanding and thusare constricted in the catheter delivery system. Since the firststent-graft component delivered to the aorta aneurysm has three stentsat different levels, the graft (the envelope of the first stent-graftcomponent) and stents can be quite large since they can be contracted toa very small diameter for easy delivery of the stent-graft through theipsilateral arteries by conventional means. If two or more stents wereat the same level, it would not be possible to contract the firststent-graft component to the same degree without reducing the size ofthe distal stents. The first stent-graft component 12 is deliveredthrough the AAA until the proximal end 13A of the first stent-graftcomponent is positioned within the proximal implantation site 30 of theaorta 22. The delivery system slowly releases the first stent-graftcomponent allowing the proximal trunk stent 48 to self-expand to form aunion between the inner wall of the undilated portion, i.e., healthyportion, of the aorta 22 and the outer wall of the proximal end of thefirst stent-graft component 12. The surgeon observes this manipulationby X-ray observation. As the delivery system is withdrawn, leaving thefirst stent-graft component in the aneurysm 28, the ipsilateral trunkstent 50 expands and then the bell-bottom stent 52 expands to form thebell-bottom. The stents 50 and 52 keep the distal ends of the legs 15Aand 15B open for insertion of the second and third stent-graftcomponents 14 and 16. The ipsilateral catheter guide wire 80 utilized toguide the first stent-graft component through the ipsilateral iliacartery 24 and through the aorta aneurysm 28 to the undilated portion ofthe aorta 22 remains behind as a guide for the insertion, connection,and implantation of the second stent-graft component 14.

The delivery system containing the contracted second stent-graftcomponent is guided back to the AAA using the ipsilateral guide wire 80in the same manner as the guide wire was used to implant the firststent-graft component. As shown in FIG. 6, the second stent-graftcomponent or ipsilateral extension 14 is comprised of a tubular sheath21 with a plurality of self-expanding stents, the proximal ipsilateralextension stent 54, the distal ipsilateral extension stent 55 andsupporting stents 60. The stents are self-expanding and are contractedwhen inserted into the delivery system. Once the delivery system hascorrectly positioned the ipsilateral extension in the modularstent-graft and is withdrawn, the stents are sequentially expanded asthe delivery system is withdrawn.

Referring to FIGS. 1 and 4, the proximal end 36 of the ipsilateralextension 14 is inserted into the ipsilateral docking site 18. As thedelivery system is withdrawn, the proximal ipsilateral extension stent54 expands, compressing the tubular sheath 21 between the ipsilateraltrunk stent 50 and the proximal ipsilateral extension stent 54. Theinternal diameter of the ipsilateral trunk stent 50 is greater than theinternal diameter opening of the restriction 62, causing a narrow waist70 to form in the sheath 21 as the proximal ipsilateral extension stent54 expands. This physically locks or secures the ipsilateral extension14 to the ipsilateral leg 15A to prevent the ipsilateral extension fromslipping out or being pulled out of the first stent-graft component. Asthe delivery system is fully withdrawn, the distal ipsilateral extensionstent 55 expands compressing the sheath 21 against the interior wall ofthe ipsilateral femoral artery 24 at the ipsilateral distal implantationsite 32.

After the surgeon confirms that the ipsilateral extension has beensuccessfully implanted into the ipsilateral iliac artery 24, acontralateral catheter guide wire 82 is then inserted into the AAAthrough the contralateral iliac artery 26. As mentioned above, thebell-bottom 42 of the first stent-graft component aids the surgeon insnaking the guide wire into the contralateral docking site 20. After theguide wire has been successfully positioned, the delivery systemcontaining the compressed contralateral extension 16, which for allintents and purposes is identical to the ipsilateral extension shown inFIG. 6, is guided along the guide wire 82 so that the proximal end 37 ofthe contralateral extension is positioned within the contralateraldocking site 20. The proximal end of the contralateral extension ispositioned in the docking site so that the first proximal contralateralextension stent 56 is positioned above or proximal to the constriction64 and the second proximal contralateral extension stent 58 ispositioned below or distal to the constriction 64. As the deliverysystem is withdrawn, stents 56 and 58, which are self-expanding, expandforcing the sheath 21 of the contralateral extension to expand out tocompress the sheath against the inner walls of the contralateral dockingsite 20. Since the outer diameter of the expanded stents 56 and 58 arelarger than the inner diameter of the constriction 64, a narrow waist 72is created in the sheath 21. This physically locks or secures theproximal end 37 of the contralateral extension into the docking site 20of the first stent-graft component. After the surgeon confirms that theproximal end of the contralateral extension has been successfullyconnected to the contralateral docking site, the surgeon manipulates thedistal end 39 of the contralateral extension into the contralateraldistal implantation site 34 of the contralateral iliac artery 26. Oncethis positioning has been completed, the surgeon carefully withdraws thedelivery system to permit the distal contralateral extension stent (notshown) to expand and compress the outer wall of the contralateralextension sheath 21 against the inner wall of the contralateral femoralartery. When the surgeon confirms that the contralateral extension hasbeen successfully implanted, the contralateral catheter guide wire isthen withdrawn. At this point the modular stent-graft has beensuccessfully implanted to repair the AAA, a repair that not onlyprotects the life of the patient but also enhances the quality of thepatient's life, since the aneurysm has been shunted out of the patient'scirculatory system and no longer functions as a hydraulic accumulator.

The radioopaque marker 66 in the constriction 64 of the contralateraldocking site 20 functions as a marker for the surgeon as he observes themanipulation of the various components during the operation. The markerpermits the surgeon to easily locate the positioning of the proximalipsilateral extension stent and the proximal contralateral extensionstent 54, 56 respectively, with respect to the restrictions 62, 64respectively.

Referring to FIG. 7, an alternative embodiment of the first stent-graftcomponent 12A of the present invention is illustrated wherein thebell-bottom 42 is angled towards the contralateral iliac orifice, makingit easier to guide the contralateral catheter guide wire 82 into thecontralateral docking site 20, as described above. In all otherrespects, the first stent-graft component is identical to thestent-graft component 12 described above. The stents 48, 50 and 52 areshown in phantom.

Referring to FIG. 8, a second alterative embodiment of the firststent-graft component 12B of the present invention is illustrated. Theipsilateral docking site 18A is free of an ipsilateral trunk stent whichis contained in the first stent-graft component 12 described above.However, the contralateral docking site 20A has a contralateral trunkstent 51 with a series of longitudinal struts 53 extending distally ordownwardly from the stents 51 biased to create a conical section withrespect to cone 44 of the first stent-graft component. In all otherrespects, the first stent-graft component 12B is identical to the firststent-graft component 12 described above.

When the alternative embodiment first stent-graft component 12B isutilized to form a modular stent-graft, the proximal end 36 of theipsilateral extension 14 is positioned slightly above the restriction 62so that when the proximal ipsilateral extension stent 54 expands, itexpands the outer wall of the sheath 21 of the ipsilateral extensionagainst the inner wall of the ipsilateral docking site 18A to seal theipsilateral extension to the first stent-graft component 12B.

The outer diameter of the proximal ipsilateral extension stent isgreater than the inner diameter of the constriction 62 causing thesheath 21 of the ipsilateral extension to form a narrow waist (notshown), thus locking and securing the proximal end of the ipsilateralextension to the ipsilateral docking site 18A to prevent the extensionfrom slipping out or being pulled out of the first stent-graft component12B. The cone 44 acts in the same manner as the bell-bottom 42 to givethe surgeon a greater target area to locate the contralateral catheterguide wire into the contralateral docking site 20A. When the firststent-graft component 12B is in the delivery system, it is compressedand struts 53 are aligned parallel to each other and adjacent to eachother. When the delivery system is withdrawn after the first stent-graftcomponent has been implanted into the proximal implantation site 30, thestruts 53 expand outwardly to expand the envelope 45 of the cone 44. Thestruts bow out at the juncture of the constriction 64A so as to helpform the narrow waist 72A at the proximal end 37 of the contralateralextension 16. After the contralateral catheter guide wire has beenpositioned within the contralateral docking site 20A, the proximal end37 of the contralateral extension 16 is positioned within the dockingsite. The delivery system is slowly withdrawn, allowing the proximalcontralateral extension stent 56 to expand, compressing the sheath 21 ofthe extension between the inner side of the contralateral trunk stent 51and the outer side of the first proximal contralateral extension stent56. The narrow waist 72A formed in the sheath 21 locks or secures theproximal end 37 of the contralateral extension to the contralateraldocking site 20A to prevent the extension from slipping out or beingpulled out of the docking site.

Referring to FIG. 9, a third alternative stent-graft component 12C isillustrated which is identical to the first stent-graft component 12described above, with the exception that ipsilateral docking site 18B ofthis first stent-graft component does not contain an ipsilateral frontstent. In contrast, in this first stent-graft component 12C, a flexiblebracer 78 is located within the component to prevent longitudinalcollapse of the ipsilateral leg 15A during implantation into theproximal implantation site 30. Alternatively, longitudinal collapse ofthe ipsilateral leg 15A can be prevented in the first stent-graftcomponent 12C described above by attaching ipsilateral leg 15A tocontralateral leg 15B by struts attached between the two legs, amembrane attached to the two legs, or by sewing the two legs together(not shown).

I claim:
 1. A modular graft assembly, comprising: a main graft componentincluding a first end and a second end and having a longitudinaldimension, said second end including a flared configuration; at leastone auxiliary graft component; and a plurality of radial expansionmembers attached to said main graft component and positioned in anon-overlapping manner along said longitudinal dimension of said maingraft component.
 2. The modular graft of claim 1, wherein said secondend is defined by a first leg and a second leg.
 3. The modular graft ofclaim 2, wherein said second leg has said flared configuration.
 4. Themodular graft of claim 2, wherein said first leg has a length greaterthan said second leg.
 5. The modular graft of claim 2, said first legfurther comprising a terminal end configured with a self-expandingradial expansion members.
 6. The modular graft of claim 2, said secondleg further comprising a terminal end configured with a self-expandingradial expansion members.
 7. The modular graft of claim 2, wherein saidmodular graft includes a first auxiliary graft component adapted toconnect to said first leg.
 8. The modular graft of claim 7, said firstauxiliary graft component further including radial expansion membersconfigured to urge said first auxiliary graft component into engagementwith said first leg of said main graft component.
 9. The modular graftof claim 8, wherein said modular graft includes second auxiliary graftcomponent adapted to connect to said second leg.
 10. The modular graftof claim 9, said second auxiliary graft component further includingradial expansion members configured to urge said second auxiliary graftcomponent into engagement with said second leg of main graft component.11. The modular graft of claim 2, wherein said flared configuration ischaracterized by having a first part having an increasing diameter and asecond part defining a terminal end of said graft and being continuouswith said first part, said second part having a generally constantexpanded diameter.